1. Field of the Invention
The present invention relates to audio playback technologies and, more particularly, to an audio player provided with the function for fast-forward playback capable of providing an acoustic output at an increased playback speed, and to an audio fast-forward playback method applied to the player.
2. Description of the Related Art
People can now make a large amount of audio data available to themselves and enjoy the audio in various ways, supported by technical aspects such as advances in audio data coding technologies, availability of large-capacity, small-sized storage devices, and improvement in network availability. Audio player for enjoying purchased music software or self-made music pieces are now highly functional; they can not only play back audio data in the order of recording but also can easily play back in a random order, skip to a next music piece, or repeatedly play back a particular music piece.
Fast-forward playback is one such function of an audio player. Generally, when a user want to listen to a part of a music piece ahead of the part being played back, the user increases the playback speed by using the function for fast-forward playback. When the playback advances to the desired part, the user returns the speed to normal. While playback may be advanced to a part ahead of the part being played back by skipping to an index recorded at the start of the data for a music piece or the data for movement, fast-forward playback is largely different from the skipping function in that the user can advance the playback while listening to an actual music piece.
Technologies for fast-forward playback include thinning out audio signals in units of samples, and thinning out audio signals in units of blocks. The former thins out digital data produced by sampling at, for example, 44.1 kHz at a rate commensurate with the required playback speed and plays back accordingly. For example, double playback speed is achieved by thinning out nth samples, where n is an odd number, and playing back even numbered samples. The latter partitions audio data into a block to be played back, a block to be dropped, and a block to be played back and so forth. For example, quadruple speed is achieved by repeating the process of playing back for one second and dropping blocks for three seconds.
One of the greatest features of fast-forward playback is that the user can listen to sound being played back as the fast-forward playback is proceeding. However, the related-art methods such as those described above have disadvantages in that, as the playback speed is increased, the user experiences significant changes in musical pitches or musical tones, or playback parts are turned into fragments of sound quite unlike the original music piece, with the result that it may be useless to let the user listen to playback. For this reason, usable playback speed is limited.